This application is directed generally to the area of controls for internal combustion engines. While the invention may find other applications, the present disclosure is directed more particularly to an engine speed control system for use with an off road vehicle, and still more particularly with a relatively small off-road vehicle adapted for turf or landscape maintenance applications, such as on a golf course, park areas or similar relatively large landscaped areas.
One particularly useful type of light truck or vehicle for golf course or similar landscaping use is made by the Jacobsen Division of Textron Inc., the owner of this application. This off-road vehicle is adapted to mount a variety of implements for working on a golf course or similar landscaping application. These implements include various hydraulically powered implements such as a sprayer for applying pesticides or fertilizers in liquid form, as well as a spreader attachment for spreading granular materials such as fertilizer, seeds, and the like, or various combinations of materials, such as are used in what is commonly referred to as top dressing of greens in golf course applications. The vehicle may also optionally be equipped with a dump body for hauling and dumping various materials or with hydraulically operated pruning equipment for trees and bushes. In order to operate the various hydraulic implements which may be utilized therewith, the vehicle is equipped with a hydraulic system including a power take-off (PTO) for providing power to the drive motors of these various implements.
In addition to the above-mentioned implements, such implements as drum aerators may be utilized. The vehicle's hydraulic system provides power (e.g. at the PTO) for a hydraulic cylinder to lower the aerator as desired for working on fairways, and to lift the aerator for example, to transport across other areas to a fairway to be aerated. Other aerators utilize reciprocating aerating heads which may also require a source of power, such as the PTO.
Other implements may also utilize the hydraulic power take-off for performing other landscape applications in golf courses or in similar environments. For example, various hydraulically powered tree pruners and saws for maintaining trees and shrubs may also be driven by the hydraulic system of the vehicle.
In order to properly utilize the vehicle in the many and varied applications and with the numerous implements or tools mentioned hereinabove, it is proposed to provide a speed control system for the engine. That is, in many jobs to be performed utilizing various ones of the foregoing implements or devices, it is desirable to maintain control of the engine speed within various limits, both to control the ground speed of the vehicle and also to control the hydraulic power take-off system for driving various implements or tools under given circumstances.
For example, when operating on or around a green, such as for top dressing or the like, it is desirable to maintain constant speed across the green, and yet maintain the ability to reduce speed and attain maneuverability, by stopping or turning at reduced speed, if desired once off the green. We have proposed utilizing what we have termed a governor mode of speed control in which the operator may select a maximum engine speed for use on greens, or other similar work in confined areas, and yet reduce speed by use (release)-of the accelerator pedal when desired, to attain maneuverability.
On the other hand, when working in relatively large open areas such as fairways or the like, it is generally desirable to maintain a fixed constant minimum speed which may be released (e.g. by braking) if and when desired. For this application we have proposed utilizing a speed control in what we have termed a throttle mode wherein a lower limit of engine rpm or speed may be selected and maintained without use of the accelerator pedal. This throttle mode of operation may also be utilized in remote or stationary applications wherein implements such as a tree pruner, or saw, or the like are to be connected to the hydraulic system of the vehicle and used while the vehicle remains stationary. These applications may also require some preset engine speed or rpm in order to provide the required hydraulic power to the implement or tool. Basically, in this mode the idle speed or lower limit of the engine speed is preset and maintained without use of the accelerator pedal, which pedal can be used to attain elevated engine speeds.
Moreover, in spreading and spraying applications, it is often desirable to maintain a given engine speed in order to drive the spreader or sprayer at the desired operating speed to maintain a given spread or spray pattern, and at the same time maintain some predetermined ground speed of the vehicle, to maintain a desired spread or spray density. The combinations of desired engine rpm and desired ground speed can be determined from suitable charts and the like. These charts may specify gear selection to maintain a given ground speed with a given engine speed, for example. However, it may prove difficult in actual applications to properly maintain engine rpm and ground speed manually. Therefore our proposed governor mode and throttle modes as discussed hereinabove permit required engine speeds to be selected and maintained for given applications.
We have also proposed to permit operation of the vehicle in what we have termed an off mode wherein neither the governor mode nor throttle mode are selected and the operator selects the engine rpm and ground speed by use of the accelerator and gear shift. We also prefer to provide an engine speed control lever which permits selection of one of two speed ranges for each of the four gears of the vehicle. This in effect doubles the number of gears effectively provided by the vehicle transmission.